Electrical connector plug



R. A. WHALEN ELECTRICAL CONNECTOR PLUG May 26, 1964 Filed Nov. 4, 1960 Fla.

INVENT RQBE T A.W A a United States Patent 3,134,631 ELECTRICAL CONNECTOR PLUG Robert A. Whalen, 5915 W. Arthur St., Milwaukee, Wis. Filed Nov. 4, 1960, Ser. No. 67,266 11 Claims. (Cl. 339-14) This invention relates to a new and improved electrical connector plug, particularly of the three terminal type wherein a ground connection is made simultaneously with the electrical connection. This application is a continuation-in-part of Whalen application, Serial No. 13,543, filed March 8, 1960, now abandoned.

The hazard of ungrounded electrical devices is pretty well recognized, and various type plugs have been designed to meet the problem. Grounding of electrical devices has been accomplished by providing gnound wires on the plug, third terminals along with the electrical connectors and a variety of collapsible third terminals. In the first type of plug, that is the ground wire type, a special Wire connection has to be made which is often ignored, leaving an exposed wire on the plug, increasing the hazard, or the ground wire is cut off. In the second type plug, the three terminal type, a special three terminal receptacle is required, which is generally not available, so the third prong is removed. In the latter type plug, the third prong is either external to the plug and therefore exposed, at it is internal to the plug when connected to a two terminal receptacle, and therefore not readily available for a ground wire connection.

The primary object of the present invention is to provide a new and improved three terminal plug, which is readily adaptable to a two terminal receptacle.

A further object of the present invention is to provide a three terminal plug which can be easily grounded when connected to a two terminal receptacle.

A still further :object is to provide a three terminal plug with a rotatable ground terminal which meets the Underwriters requirements for rigidity and removability.

These objects are accomplished by providing a pivoted ground terminal on the face of the plug which swings down between the two electric terminals. The body of the plug conforms to the accepted plug silhouette with the pivot for the ground terminal located within the plug. A resilient diaphragm is provided adjacent the pivot point to provide a bias for the ground terminal and relieve the body of stresses when rotated on the pivot. The ground terminal is rotated into a channel formed in the face of the plug with only a small part of the end of the ground terminal projecting beyond the plug. A plug having the same contour as the chamfer is inserted into the chamfer when the ground terminal is in an operative position to provide a rigid support for the ground terminal. Relief grooves are provided along either side of the chamfer to relieve the plug body of stresses created when the ground terminal is rotated into the body. The end of the terminal is designed so that a wire may be easily attached to the third terminal if a three terminal receptacle is not available and a ground is desired.

One advantage of this plug structure is that it is weather proof for either indoor or outdoor use.

Other objects and advantages will be pointed out in, or be apparent from, the specification and claims, as will obvious modifications of the single embodiment shown in the drawings, in which:

FIG. 1 is a side elevation of the electrical connector with the ground terminal extended.

FIG. 2 is a top view of the electrical connector shown in FIG. 1.

FIG. 3 is a front elevation of the connector shown in FIG. 1.

FIG. 4 is taken on line 44 of FIG. 3.

and an opening 38.

FIG. 5 is similar to FIG. 4 showing the ground terminal in the inoperative position.

FIG. 6 is a side view of a modified ground connection.

FIG. 7 is a side elevation of the modified connection shown in FIG. 6.

FIG. 8 is a perspective view of the contoured plug.

As seen in the drawings, contact blades 10 and 12 and ground terminal 14 are connected to electric leads 16, 18 and 20 respectively and molded within plug body 22. The contact blades 10, 12 are conventional in structure and are connected to the leads by crimp type connectors. Ground terminal 14 is made from bar stock and is provided with an orifice 24 through which pivot 28 extends so that the ground terminal can be rotated from an operative to an inoperative position. The pivot is formed by rolling one part of a flat piece of stock to form a hollow bar having a small amount of transverse resilience which assures positive connection between the pivot and the ground terminal. As seen in the drawings, the interior portion of the pivot will be filled with the plug body material when molded. The other part of the flat stock is bent to form a crimp type lead connection for lead 20. In an alternative arrangement for the pivot, a tube is crimped on the lead wire and then bent to-form the L shape shown in the drawings. The pivot will then be tubular in cross section.

The ground terminal can be rotated into chamfer 30 provided in the face of the plug (FIG. 5) when a three terminal receptacle is not available. As seen in the drawings, a small orifice 32 is provided in the plug about the end of the ground terminal, leaving diaphragm 34 above the pivot point for the terminal. When the plug is molded with the ground terminal in the operative position, the plug material will form a holding surface for the ground terminal in the operative position. When the plug is molded with the ground terminal in the inoperative position, the diaphragm will be located in a plane parallel to the axis of the ground terminal to relieve stresses in the plug body when the ground terminal is rotated to the operative position. A plug 35 of rigid material is contoured to fit into the chamfer when the ground terminal is in the operative position to rigidly support the ground terminal. This plug is removed when the ground terminal is to be rotated into the chamfer. On rotation of the ground terminal, the interior end of the terminal will flex the diaphragm, preventing any distortion from occurring in the plug body. When the ground terminal is rotated, the entire upper portion of the plug would be distorted, sometimes resulting in the upper portion of the plug splitting. The diaphragm also protects the pivot and ground from, foreign matter which may collect in the orifice. The diaphragm may be omitted for a specific application, leaving an opening above the pivot point. Where it is desired to rotate the ground terminal into a chamfer along the top of the plug body, a diaphragm should be provided below the pivot point of the ground terminal. I

The chamfer 30 is formed with an internal cavity 36 The internal cavity is just large enough to seat the ground terminal and the opening is made small than the cavity so that a small amount of force is required to move the ground terminal through the opening and into the cavity, thereby holding the ground terminal in the chamfer. Relief grooves 37 are provided on either side of the chamfer to relieve the body of any stresses created when the ground terminal is forced through the opening 38. The internal cavity is set back from the face of the plug by the depth of the opening 38 so that the ground terminal will not engage the face of the receptacle when positioned in the chamfer. When the ground terminal is rotated to an operative position, the bias of the diaphragm will provide some force in returning the terminal to a fully extended position.

The ground terminal is provided with grooves 26, 26 at its outer end immediately below the surface of the plug body (FIG. As seen in FIG. 6 clip 40 can be securely fastened to the ground terminal of the plug by holding the clip below the cbamfer so that the fingers of the clip slide into grooves 26, when the ground terminal is moved into the chamfer. The ends of the clip are bent to form lugs 42, 42 which lock the clip in position. The clip is crimped to a ground wire 44 which can be connected to a ground lead where a three terminal receptacle is not available. With this simple connection, the plug can be used with the conventional two plug receptacle Without any major Wiring connection, and leaving only a minimum of exposed wire.

Although but one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

I claim:

1. A self-grounding electrical attachment plug comprising a plug body made of resilient electrically non- .conducting material and having at least one electric contact,

a ground terminal,

pivot means molded within said plug body, said ground terminal being pivoted on said pivot means and thin flexible means molded integral with and of the same composition as said plug body to contact and allow the ground terminal to be rotated into the plug body.

2. An electrical connector plug comprising a plug body of resilient insulating material having a pair of electrical contact blades projecting therefrom,

a ground terminal parallel to and spaced from said contact blades,

and pivot means supporting one end of the ground terminal within said body, so that it is rotatable from an operative to an inoperative position,

said body including a groove to receive the ground terminal when rotated to the inoperative position and a thin resilient diaphragm means integral with and of the same composition as the plug body adjacent the pivot point of the ground terminal to relieve the body of stresses created by the said one end of the ground terminal when the ground terminal is rotated.

3. An electrical connector according to claim 2 wherein said pivot forms the ground connection for the ground terminal.

4. An electrical connector according to claim 2 wherein said groove is located between the electrical contacts and the ground terminal is spaced from the face of the plug when rotated into the groove.

5. An electrical connector according to claim 4 including removable plug means contoured to seat firmly in said groove when the ground terminal is in the operative position to prevent the ground terminal from moving on the pivot.

6. An electrical connector plug comprising, a body of insulating material having a pair of electrical contact blades projecting therefrom and a contoured groove extending therebetween, a ground terminal having one end external to the plug and the other internal to the plug,

means for pivoting said terminal from a position parallel to the blades to a position wihin said groove, and diaphragm means integral with the body adjacent the internal end of the ground terminal to relieve the body of stresses created by the movement of the internal end of the ground terminal when rotated on the pivoting means, and to provide a holding force on said ground terminal in both of its positions in the plug body.

7. An electrical connector plug according to claim 6 wherein the pivoting means includes a hollow shaft molded within the plug, said shaft being flexible to assure positive contact with the ground terminal.

8. The combination with an electrical plug of the type having an internally pivoted ground terminal which can be rotated from an operative to an inoperative position and having resilient diaphragm means adjacent the ground terminal for relieving stresses in the plug when the terminal is rotated to the inoperative position, of means for including a ground connection when the ground terminal is in the inoperative position comprising, a ground lead wire, a pair of grooves on the ground terminal having a forked connecting means for engaging the grooves on the ground terminal, said connecting means including a pair of lugs to engage the face of the plug when the connecting means is secured to the ground terminal.

9. An electrical connector plug comprising, a body of insulating material having a pair of electrical contact blades projecting therefrom and a contoured chamfer means extending therebetween, said chamfer means including an interior cavity of circular cross section and an opening connected thereto having a width less than the diameter of the cavity, a ground terminal having an external end and an internal end, means for pivoting said terminal from a position parallel to the blades to a position within said cavity, said opening providing a resistance to movement of said terminal when in the cavity and diaphragm means adjacent the internal end of the ground terminal and molded integral with the body to relieve the body of stresses created by the movement of the internal end of the ground terminal when rotated into the chamfer.

10. An electrical connector plug according to claim 9 including a removable plug contoured to fit into the chamfer means to support the ground terminal when in the operative position.

11. An electrical connector plug according to claim 10 including stress relief means on either side of the chamfer means to allow the opening to expand when the ground terminal is rotated into the cavity.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A SELF-GROUNDING ELECTRICAL ATTACHMENT PLUG COMPRISING A PLUG BODY MADE OF RESILIENT ELECTRICALLY NONCONDUCTING MATERIAL AND HAVING AT LEAST ONE ELECTRIC CONTACT, A GROUND TERMINAL, PIVOT MEANS MOLDED WITHIN SAID PLUG BODY, SAID GROUND TERMINAL BEING PIVOTED ON SAID PIVOT MEANS AND THIN FLEXIBLE MEANS MOLDED INTERGRAL WITH AND OF THE SAME COMPOSITION AS SAID PLUG BODY TO CONTACT AND ALLOW THE GROUND TERMINAL TO BE ROTATED INTO THE PLUG BODY. 